Alan sez, "Ann Makosinski, a Canadian girl scientist, describes her Google Science Fair submission: an LED flashlight that runs solely on the heat of the human hand. According to the GSF site she is one of 15 worldwide finalists at this point. The Hollow (Thermoelectric) Flashlight - Google Science Fair (Thanks, Alan!) READ THE REST

bzishi
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2013-07-03T20:17:31Z —
#2

Let's see: 5mW/cm^2 * 1.75 m^2 (avg skin area per human) * 7 billion = 613 GW. Wikipedia says that the world uses about 2.3 TW. We will need to start conserving energy if we wish to have a Matrix-style future where energy is harvested from our skin.

In any case, this is a smart kid, but a windup device would be more effective. The best you are going to get thermoelectrically from a flashlight handle is ~50 mW, while you can easily get more than a watt from a dynamo that charges into a capacitor or a battery.

daneel
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2013-07-03T20:21:35Z —
#3

I am sad her name isn't Jamie.

50thomas50
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2013-07-03T20:25:28Z —
#4

Cory - why do you differentiate between "girl" and "boy" scientists?

peregrinus_bis
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2013-07-03T20:31:42Z —
#5

Genius. She's a bright spark. Would it work better (brighter) if a tight-fitting sleeve of the do-wha-diddy fed the power?

cellocgw
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2013-07-03T20:57:47Z —
#6

What -- nobody posting smart ass remarks about how a TEC-powered flashlight works best with a "hot girl" ?

Antinous
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2013-07-03T21:56:31Z —
#7

50thomas50:

Cory - why do you differentiate between "girl" and "boy" scientists?

What part of quotation marks are you having trouble with?

Antinous
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2013-07-03T21:57:13Z —
#8

So... would this thing just be on for five months here in Palm Springs?

kibrit
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2013-07-03T21:58:35Z —
#9

Good for her, but this is not science. She is not investigating phenomena through the scientific method.

Even if no one had thought to combine a thermoelectric cell with a light before, it would still not be an invention, because sticking two already-existing things together is not an invention.

Someone on reddit pointed out that the girl's father is a mechanical engineer, but I'll give her the benefit of the doubt on that.

kibrit
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2013-07-03T22:03:41Z —
#10

Depends on the delta T of the air. Thermoelectric generators require a temperature differential to work.

ridley_john
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2013-07-03T22:34:23Z —
#11

Hm, 0.5mw for a usable LED brightness? Every LED I've seen uses a minimum of 20mw. Add 50% efficiency of the upconversion, stepping from 0.5 volts to 2.5 volts and you need 5 * 2 * 20mw = 200mw at 0.5 volts.

Ah, after watching the end of the video, I see. She's greatly underdriving the LEDs and they're really, really, really dim.

This also is highly dependent on the ambient air temperature and won't run for long unless there's a breeze.

dragonfrog
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2013-07-03T22:38:02Z —
#12

Yes, but to get a steady watt from a hand crank, you have to be cranking it the whole time. If your flashlight works acceptably on 50 mW, that's 1 minute cranking for ever 20 of use.

I'll take 0 minutes cranking per infinity minutes of use, myself...

50thomas50
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2013-07-04T01:01:55Z —
#13

Ask Cory why he calls her a "girl".

Antinous
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2013-07-04T01:28:52Z —
#14

The entire post, except for "Alan sez" is a quote from someone else.

Jardine
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2013-07-04T05:37:38Z —
#15

It probably wouldn't work at all in Palm Springs. If it did, it wouldn't work very long. It's my understanding from a previous article that it would work best in cooler temperatures, but even then it only works for about 20 minutes. By that time, the tube would heat up closer to the temperature of the user's hand and stop generating electricity. Right now at 1:30am, it's 22, feels like 29 here. So it would probably work poorly for a few minutes and then stop.

Antinous
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2013-07-04T05:52:51Z —
#16

It's 45° to 50° here every day now, 37ish at midnight.

doctorow
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2013-07-08T19:23:28Z —
#17

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